I was thinking of getting this light for home defense and or outdoor use. What I want is something that will illuminate focused on something about 100 yards away and also help light up an area with ambient light indoors. I want to be able to swap this light between a Glock for home use and quickly mount it onto an AR for outdoor use if necessary. Is what I am thinking of practical? Or should I just get one for the Glock and one for the AR?

I like something like the TLR-1HL/TLR-2HL for pistols and/or close range lightning on a rifle...

For something longer range you might look at the TLR-1HP which would give you much more distance but less throw width (and would not work well on a pistol imo)

TLR-1 HL

Just bought my second.  Can't beat them